updated 06:10 pm EDT, Tue July 6, 2010

Firefox 4 beta 1 uses whole new UI, HTML5

Mozilla after a brief tease has released Firefox 4 beta 1, the first public, stable version of its next major browser. It centers on a brand new UI with tabs on top, as with Chrome, but adds more support for HTML5 and Google's new WebM open video standard. Extensions are equally important and are now both easier to manage and no longer need a browser restart to load.

Numerous other changes should also help both performance and security, such as a basic layer of hardware graphics acceleration, improvements to the CSS3 and JavaScript renderers, and a fix for a CSS-related privacy flaw that in any browser, not just Firefox, could reveal some of the browser's history. Mac users get an extra update as OOPP-based plugins should now work in their version of the app.

Beta 1 is available for Linux, Mac and Windows systems today. Mozilla hasn't said when it expects to get a release candidate or a final build, but it often has a final version no more than a few months after the first beta appears.